qmath_p.h

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QMATH_P_H
#define QMATH_P_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <qmath.h>
#include <private/qglobal_p.h>
#include <qtransform.h>
 
QT_BEGIN_NAMESPACE
 
static const qreal Q_PI   = qreal(M_PI);     // pi
static const qreal Q_MM_PER_INCH = 25.4;
 
inline QRect qt_mapFillRect(const QRectF &rect, const QTransform &xf)
{
    // Only for xf <= scaling or 90 degree rotations
    Q_ASSERT(xf.type() <= QTransform::TxScale
             || (xf.type() == QTransform::TxRotate && qFuzzyIsNull(xf.m11()) && qFuzzyIsNull(xf.m22())));
    // Transform the corners instead of the rect to avoid hitting numerical accuracy limit
    // when transforming topleft and size separately and adding afterwards,
    // as that can sometimes be slightly off around the .5 point, leading to wrong rounding
    QPoint pt1 = xf.map(rect.topLeft()).toPoint();
    QPoint pt2 = xf.map(rect.bottomRight()).toPoint();
    // cut short if the result will be an empty QRect anyway
    // side effect: avoids overflows in the calculations below
    if (Q_UNLIKELY(pt1.x() == pt2.x() || pt1.y() == pt2.y()))
        return QRect();
    // Normalize and adjust for the QRect vs. QRectF bottomright
    return QRect::span(pt1, pt2).adjusted(0, 0, -1, -1);
}
 
QT_END_NAMESPACE
 
#endif // QMATH_P_H